I've had a couple of additional backchannel responses to this (thank you) but nothing terribly decisive. Is the question too diffuse, I wonder? Too obscure? How would one go about running something like this down? What would be some good industry publications to check to try to track the emergence of "archive" as a computer systems term?
OED doesn't offer a usage in relation to computing or data before 1978, but this seems late to me; certainly Wang was using the language of an "archive" disk for much of the 1970s.
Best, Matt